Soil penetration and friction resistance measuring apparatus



Sept. 15, 1964 1 Filed Dec. 7, 1960 HEEREMA MEASURING APPARATUS 2Sheets-Shet 2 r fl 5/ 20 c *2? 1' I 75 26 260/ v l N 62 I x E I 87INVENTOR 5 E 70- Pieter s. HEEREM 37 BY M ITTOANE) United States Patent3 148 538 son. rnNnrnArroN AND rurerroN nnsrsrANci: MEASURENG APPARATUSPieter S. Heerema, RR. 1, Beebe, Quebec, Canada Filed Dec. 7, 1969, er.No. 74,259 Claims priority, application Canada, Nov. 23, 1960, 811,681(Ilaims. (ill. 73-84) This invention relates to an apparatus for subsoilinvestigation, particularly for the predeterrnination of suitable pilelengths and the prediction of permissible pile loads.

One way of predetermining pile lengths on a pile driving job is to drivetest piles in advance. In the case of a concrete pile job, an elaborateset-up is necessary before the commencement of the permanent piledriving. Therefore, steel index piles are sometimes driven and acorrelation established, which enables the designer to estimate theproper length of the permanent concrete piles. Such an index givesrather crude results in that it supplies no data on subsoil conditionsbelow its point. And, its driving record may lead to recording thepresence of non-existent hard layers. Furthermore, a long steel indexpile can absorb so much driving energy and build up so much frictionover its length, that the large number of blows per foot to drive it maygive the false impression that a hard layer has been reached.

A better expedient is the so-called Dutch Cone Penetration Method,particularly when the cone used is provided with a soil frictionmeasuring device, or sleeve. Pressures are measured hydraulically,through a device located at the top of the column. The column isgradually lengthened by coupling additional lengths as the cone isforced down hydraulically. However, a sure footing must be provided forthe instruments. For example, in deep water, a strong platform must beconstructed usually over already driven piles. The limit of penetrationcapacity, usually about ten tons, is soon reached. Then, furtherpenetration is only possible with the aid of drilling, jetting, orpercussion installations. This method is, therefore, extremelytime-consuming and costly in deep Water regions, where deep penetrationinto hard layers is necessary.

The Applicants Development The applicant has now evolved an apparatuswhich combines the speed and ease of the driving of a steel index pilewith the information that the slow and costly penetration test provides.The applicant employs a drivable metallic index pile of normal pile sizewhich is provided, at its tip, with a sleeve movable relative to thepile and a cone further movable relative to the sleeve. Hydraulic meansis built into the tip of the pile to advance the cone and the sleeve.Pressure lines running up through the pile connect this hydraulic meanswith a hydraulic pump. Manometers are conveniently placed so that theobserver can make two readingsthe first indicating the pressure requiredto move the cone, and the second indicating the pressure needed to movethe cone and the sleeve. The first reading provides data on theresistance of the soil. The second reading indicates the pressure neededto move the cone and sleeve, thus providing a basis for calculatingfriction of the soil. Means is provided for relieving the pressure whenthe cone and sleeve have moved a predetermined distance, when drivingthe pile may be resumed.

Having thus generally described the nature of the invention it will bereferred to in more detail by reference to the accompanying drawingsillustrating preferred embodiments, and in which FIGURE 1 is aperspective view of a pile driving set-up 3,148,538 Patented Sept. 15,1964 showing a cone pile according to the invention in the process ofbeing driven.

FIGURE 2 is a side elevation partly broken away, illustrating a testpile according to the invention.

FIGURE 3 is a cross-section along the line 3-3 of FIGURE 2 on a greatlyenlarged scale showing the tip portion of the test pile.

FIGURE 4 is a cross-section as along the line 44 of FIGURE 3.

FIGURE 5 is a cross-section as along the line 5-5 of FIGURE 3.

Referring more particularly to FIGURE 1 of the drawings, a pile drivinginstallation employing the applicants test cone is illustrated. A piledriver M having a pile driving hammer H is mounted on a suitable base N,in this case, a floating base on water W overlying a soil bed S. Thepile driver M is shown in the process of driving a test pile P,according to the invention. The preferred pile illustrated is a hollowsteel pile P having a main body portion 15 and an end portion 17 ofreduced diameter. The body of the pile is preferably provided withopenings 18 extending from the wall to its bore to allow water to enterfreely so as to equalize the pressure inside and outside the pile. Theend of the reduced portion 17 is provided with a frustroconical hollowhead 19. Mounted within the end of the hollow head 19 is a sleeve Aprovided with an annular outstanding shoulder portion 23 which abuts theannular end of the head 19 and is welded to it as at 20. Within thesleeve A is mounted a cylindrical housing B including a cylinder 27housing a piston C. The piston is provided with an annular packing ring33.

The housing B is provided with a boring 35 constituting an hydraulicfluid inlet and with a boring 37 constituting an hydraulic fluid outlet.A passage 39 in the wall of the housing B leads from the outlet 37 tothe foot of the chamber 27. The piston 29 is provided with a valvechamber 41, housing a release valve assembly including a plug 43 urgedinto closed position by a spring 45. The plug 43 seats on a valve seat47 screwed into the tapped lower end of the chamber 41 and having anorifice 48. The valve plug 43 is provided with an orificed tip 49 whichnormally projects through the orifice 48 beyond the sleeve 47. A passage51 in the body of the piston C leads from its upper face tocommunication with the chamber 41.

The housing A has a downwardly extending skirt 26 offset from the lowerend of the housing B and internally threaded as at 26a to receive theexternally threaded collar portion 59 of a tapered tip member D. Theinner surface of the collar portion 59 embraces the outer wall of thehousing B. The tip member D has shoulders 61 and 62 to either side ofthe collar portion 59 respectively abutting the lower ends of the sleeveA and housing B respectively. The tip D is provided with a cylindricalbore 69 extending axially through it and having an enlarged upperportion 71 leading from the cylinder 27.

Operating within the bore 69 and its enlarged portion 71 is a piston Ehaving a head 75. The tip member'D has a cylindrical shank 67. A sleeveF has a cylindrical portion 79 engaging the outside of the shank 67. Thesleeve F has a bore 81 with an enlarged upper portion 83 incommunication with the bore 69 of the tip D. The sleeve F is adapted foraxial movement relative to the shank 67. The lower end of the member Fis tapered as at 85 to meet a cylindrical end portion 87. On the endportion 87 is mounted a cone G having a cylindrical bore 88 slidablyreceiving the end portion 87. The cone G is connected to a lower portion91 of the piston E operating in the bore 81 of the sleeve 77. A flange93 is provided on the piston E as shown slidable in the enlarged part 83of the bore. The part 91 of the piston E is connected to the cone G by aprojecting screw portion 95 wich threadably engages a tapped bore 97 inthe cone G.

Hydraulic pressure is supplied to the inlet 35 through a flexible tube36. This tube can be made of rubber or plastic material with a verythick wall and a small orifice to carry oil. The tube 36 leads throughthe bore of the hollow pile F and out through an opening 38 in the topof the pile and, from there down to where it is rolled in a coil L, andthen from the coil to the hydraulic pump K. The outlet 37 may beconnected to a similar exhaust line 40 which extends upward through thebore of the pile P, to above water level, or this line 40 may be omittedand escaping oil, escaping from the outlet 31 allowed to enter the waterwhich fills the interior of the pile P.

The soil at test level is usually under great pressure and tends toforce itself in between the moving surfaces. The testing apparatus ofthe invention is therefore provided with a pressure equalizing systemwhich will now be described in conjunction with other means forpreventing ingress of soil into the working parts of the device. Forexample, the foot 67 is provided with several channels 68 leadingthrough it from the bore 69 to the outer surface of the foot 67.Likewise, the lower end of the sleeve F is provided with channels 70leading from the bore 81 to the outer surface. The housing B is providedwith a channel 28 leading from the inlet 35 to the channel 30, which, inturn, leads to the chamber 71. These borings are straight line boringsas indicated and provided where necessary with plugs 100 to close offaccess ports used in making the borings. The purpose of the channels 68and 70 is to equalize the pressure on the inside of the cone bore 88 andall the way up through the bores 83, 69, etc. This helps to prevent theingress of soil between the cone and the foot 87 and between the sleeveF and the foot 67.

In addition, a gasket 76 is held in a groove on the inner wall of thecone G to act between the cone G and the foot 88 and between the sleeveF and the foot 67. A gasket 78 is provided in a groove in the inner wallof the sleeve F to act between the sleeve F and the foot 67. Thesegaskets help to block the soil attempting to enter between therelatively moving surfaces of the cone G and foot 88 and of the sleeve Fand the foot 67 Operation In operation, the pile F is driven by thehammer H of the pile driver in the same way as a permanent pile, untilits lower end reaches a depth where readings of the soil resistance andthe friction are needed. At this point, driving is interrupted andhydraulic pressure is applied against the piston C by feeding oil intothe chamber 27 through the fluid entrance 35 from the hydraulic system.This forces the piston C in a downward direction. The piston C in turnpushes the piston E downwards and thus the cone G to the point where theflange 93 contacts the shoulder 84 of the sleeve F. At this point areading is taken of the pressure that has been required to move thesleeve F and the cone G. Then, hydraulic pressure is again applied tothe piston C which continues to depress the piston E which depresses thesleeve G to a point where the finger 49 of the valve 43 contacts theface 61, thus releasing the pressure in the cylinder 27. At this point,a further reading is taken of the pressure that has been required tomove the cone G alone.

From the respective readings, namely (a) that taken at the moment wherethe cone G is fully depressed on the sleeve F, and (b) at the momentwhere the sleeve F is fully depressed, there can be calculated theresistance of the soil to the penetration of the cone and the resistanceof the cone plus the sleeve respectively. Appropriate furthercalculation gives the resistance of the soil and the frictionalresistance to the advance of the cone and sleeve.

When the sleeve or sleeve end cone are being thrust ;steels are employedfor the parts of the pile.

4 into the soil by hydraulic pressure, any upward movement of the pile Pis prevented by the frictional resistance of the soil acting on thepile.

Cone and frictional readings can be alternated with pile driving andtaken at any required depth and interval. The number of strokes perfoot, cone resistance, and friction of the soil may thus be determined.After the required depth is reached and all readings have been taken,the index pile with test assembly can be with drawn and used at otherlocations. The equipment of the pile with the slip cover 14 permitsremoval of the index pile from deep penetration.

The cone and sleeve are designed in such a way that they resist thehardest pile driving into very compact soil layers, without damage,bending, buckling or fine soil entering into and jamming the device.

For penetration into extremely hard soil, special alloy A preferred conehas a projected area of 25 square centimeters, and an angle of 60 fromthe axis. The sleeve embraces a cross-sectional area of 250 squarecentimeters. A suitable index pile is a thick walled steel pipe eightinches to fourteen inches outside diameter, gradually increasing intobigger diameters of twenty inches to twenty-four inches and even more,according to the length of the pile and the problem of handling such along pile without bending. In a practical operation for underwater piledriving, a barge with a seventy-five ton derrick, with provision forone-hundred and fifty ton pull sets a twenty-four inch index pile of thetype described, up to one-hundred and sixty feet long. Then, a flyingMcKiernan S10 steam hammer is used to drive the pile. When driving tothe water level, subsequent lengths of dimensions suited to requirementsmay be welded on and driven down to reach the required depth ofpenetration. If a seventy-five ton or even a one-hundred and fifty tonpull will not remove the index pile, jetting may be employed. In thisway, in one hundred feet of water a test of two hundred feet can usuallybe accomplished in from three to six hours. This is a big improvementover previous comparable soil investigation methods which might takebetween a week and two weeks at a time, because of the necessity ofbuilding and removing a temporary platform for the testing instruments.

I claim:

1. A test pile, comprising in combination a main driving body ofsubstantially standard pile dimensions, said body having an upper endadapted to receive the blows of a pile driver and a lower extension ofreduced diameter, the lower end of said extension carrying a testassembly comprising a housing portion, and a cylindrical foot extendingaxially from the housing portion, a sleeve slidably mounted on the footfor limited axial movement relative thereto, a cone mounted for slidablemovement on the lower end of said sleeve, hydraulic means in saidhousing position for urging said cone axially of said sleeve through agiven stroke and for urging said sleeve axially along said foot througha given stroke, hydraulic communications extending from a source ofhydraulic pressure through said pile body to said hydraulic means, andmeans external to the pile and connected to said hydrauliccommunications for measuring the resistance exerted by said conethroughout the cone stroke and by the cone and sleeve throughout thesleeve stroke.

2. A test pile, comprising in combination a main driving body ofsubstantially standard pile dimensions, said body having an impactdriving head and a lower extension of reduced diameter, the lower end ofsaid extension carrying a test assembly comprising a housing portion, atapered portion below the housing portion, and a cylindrical footextending axially from the tapered portion, a sleeve slidably mounted onthe foot for limited axial movement relative thereto, said sleeve beingprovided with a lower foot with the lower end of reduced diameter, acone mounted for slidable movement on the lower end of said sleeve,hydraulic means in said housing portion for urging said core axially ofsaid sleeve through a given stroke and for urging said sleeve axiallyalong said foot through a given stroke, hydraulic communications leadingthrough said body from a source of hydraulic pressure to said hydraulicmeans, and means external to the pile and connected to said hydrauliccommunications for measuring the resistance exerted by said conethroughout the cone stroke and by the cone and sleeve throughout thesleeve stroke.

3. A test pile, comprising in combination, a main body of substantiallystandard pile dimensions, a lower extension of reduced diameterextending from said body, and on said extension a test assemblycomprising a housing portion, a tapered portion below the housingportion and a cylindrical foot extending from said tapered portion, asleeve slidably mounted on said foot for limited movement relativethereto in an axial direction, said sleeve being provided with a lowerend of reduced diameter and a cone mounted for sliding movement on saidsleeve lower end, said test assembly housing being provided with anupper piston-receiving cylinder and an axial bore leading from saidcylinder through said tapered portion and said foot, and the sleevebeing provided with an axial bore in alignment with the axial bore ofthe tapered portion of the foot and having an enlarged upper portionproviding a shoulder, a first piston operating in said cylinder, asecond piston operating in the bore of said tapered portion and foot andthe channel of said sleeve and connected to said cone, said secondpiston having a flange spaced from its lower end, means for supplyinghydraulic fluid to the cylinder to operate said piston and means forrelieving said fluid pressure at the lower end of the stroke of saidfirst piston, said first piston being in contacting alignment with thesecond piston whereby when the first piston is depressed to a certainpoint it depresses the second piston to depress the cone, the secondpiston being provided with lost motion means for engaging said sleevewhereby when the second piston is depressed to a further point todepress said sleeve until at a predetermined point of depression thepressure is relieved, and means for indicating the pressure required tomove the piston whereby the penetration resistance of the sleeve andcone and the cone alone may be determined.

4. A test pile as claimed in claim 2 in which said foot has at least onepressure relieving channel extending therefrom from its bore to its facethereby to relieve pressure between the bore and the face and saidassembly above said foot having at least one channel leading from thebore to the face and communicating with the upper side of the pistonreceiving cylinder.

5. An assembly for test piles comprising a housing portion, a taperedportion below the housing portion and a cylindrical foot extending fromsaid tapered portion, a sleeve slidably mounted on said foot for limitedmovement relative thereto in an axial direction, said sleeve beingprovided with a lower end of reduced diameter and a cone mounted forsliding movement on said sleeve lower end, said test assembly housingbeing provided with an upper piston-receiving cylinder and an axial boreleading from said cylinder through said tapered portion and said foot,and the sleeve being provided with an axial bore in alignment with theaxial bore of the tapered portion of the foot and having an enlargedupper portion providing a shoulder, a first piston operating in saidcylinder, a second piston operating in the bore of said tapered portionand foot and the channel of said sleeve and connected to said cone, saidsecond piston having a flange spaced from its lower end, means forsupplying hydraulic fluid to the cylinder to operate said piston andmeans for relieving said fluid pressure at the lower end of the strokeof said first piston, said first piston being in contacting alignmentwith the second piston whereby when the first piston is depressed to acertain point it depresses the second piston to depress the cone, andwhen the second piston being provided with means for engaging the sleevewhereby when the second piston is depressed to a further point todepress said sleeve until a predetermined point of depression thepressure is relieved, and means for indicating the pressure required tomove the piston whereby the penetration resistance of the sleeve andcone and the cone alone may be determined.

References Cited in the file of this patent UNITED STATES PATENTS2,640,351 Jourdain June 2, 1953 FOREIGN PATENTS 1,095,398 France Dec.22, 1954 79,768 Netherlands Nov. 15, 1955

1. A TEST PILE, COMPRISING IN COMBINATION A MAIN DRIVING BODY OFSUBSTANTIALLY STANDARD PILE DIMENSIONS, SAID BODY HAVING AN UPPER ENDADAPTED TO RECEIVE THE BLOWS OF A PILE DRIVER AND A LOWER EXTENSION OFREDUCED DIAMETER, THE LOWER END OF SAID EXTENSION CARRYING A TESTASSEMBLY COMPRISING A HOUSING PORTION, AND A CYLINDRICAL FOOT EXTENDINGAXIALLY FROM THE HOUSING PORTION, A SLEEVE SLIDABLY MOUNTED ON THE FOOTFOR LIMITED AXIAL MOVEMENT RELATIVE THERETO, A CONE MOUNTED FOR SLIDABLEMOVEMENT ON THE LOWER END OF SAID SLEEVE, HYDRAULIC MEANS IN SAIDHOUSING POSITION FOR URGING SAID CONE AXIALLY OF SAID SLEEVE THROUGH AGIVEN STROKE AND FOR URGING SAID SLEEVE AXIALLY ALONG SAID FOOT THROUGHA GIVEN STROKE, HYDRAULIC COMMUNICATIONS EXTENDING FROM A SOURCE OFHYDRAULIC PRESSURE THROUGH SAID PILE BODY TO SAID HYDRAULIC MEANS, ANDMEANS EXTERNAL TO THE PILE AND CONNECTED TO SAID HYDRAULICCOMMUNICATIONS FOR MEASURING THE RESISTANCE EXERTED BY SAID CONETHROUGHOUT THE CONE STROKE AND BY THE CONE AND SLEEVE THROUGHOUT THESLEEVE STROKE.